Expert: Stephen Hayes - 6/22/2010

Question
QUESTION: What can I do to fix my cracked tile in my kitchen?? I have a crack that existed before I put down my kitchen. I covered the crack with poured cement,put the crack came through 3 inches of tile cement and through the the tile too! I heard someone mention a membrane substance. Will it work ??? What els can I use??? I will have to remove 8 tiles in my kitchen...Please help me !!..Thanks...Larry

ANSWER: Hi Larry;From your question I think you are telling me that you have ceramic tile in your kitchen, that there was a crack in the concrete subfloor that you tried to correct by using additional concrete, that after the tiles were installed, tiles installed over that repaired area cracked, and the cracks in the tiles mirror the size, shape, and location of the original crack in the concrete.  Please get back to me to let me know if there are any changes to what I have indicated.  I assume that the concrete was tested for any moisture problems prior to the installation of the tiles, and that the surface of the concrete was level and flat throughout the entire area where the tiles were installed.  Also, let me know the date of installation, and when the cracks in the tiles first began to be seen.

When I hear back from you, I will have a better understanding of your installation, so I can respond to your question.

Hope to here from you soon.

Cordially,

John Michaels

---------- FOLLOW-UP ----------

QUESTION: Hi John,
Yes ,everything you quoted me was correct.The original crack on my subfloor mirrored my crack tile about 2 years after I installed the tile: this was 6 years ago. I live in a 3 story condo and we about 20 condo's sitting on this slab of concrete. No it was never tested for water

Answer
Hi Larry;I can't see your installation, so my answers are good educated guesses based upon years of experience viewing installations of all types of floor coverings when consumer problems arrise.  Since concrete is absorbent and always moves, cracks in concrete could be a moisture problem, and the overwhelming causes of any type of floor covering failures are moisture related.
Moisture evaporates upwards and takes the path of least resistance.  If there is a moisture problem, its source, which needs to be solved BEFORE any new flooring is installed, may be many feet away from the cracked area.  The problem could also be caused by installation errors that might include not enough time allowed for the mortar adhesive, used to install the tiles, to
properly set up, or too long a time was allowed for adhesive set up so the adhesive partially skinned over, allowing movement in the tiles.  You may not feel that movement, however, even if slight movement exists, tiles will crack.  Perhaps the concrete used for the patching of the cracks in the concrete was not allowed to fully dry before the tiles were installed.  Adhesive used to install the tiles have two 'grabs'.  On 'grab' is the adhesive onto the back of the tiles.  The other 'grab' is the adhesive to the concrete.  If the 'grab' of the adhesive is greater than the bond of the concrete used for patching the cracks in the concrete slab, that bond will cause the patching concrete to lift off or move from the slab concrete.

You have made an investment and you need to protect that investment.  My suggestion would be to take up the 8 cracked tiles, which, I assume, are immediately adjacent to each other, make sure enough adhesive was used during the installation to provide a 100% adhesive transfer to the back of the tiles, and measure the trowel ridges to make sure a proper trowel size was used.  Then carefully scrape away the adhesive residue down to the surface of the concrete.  The concrete, in that area, should be tested for moisture.  The testing is not cheap.  There is a Company that is headquarted in Washington, DC and Philadelphia, PA, ASTM, who does extensive research and then writes testing methods that should be used.  They write those testing methods for, just about, everything that you and I use.  They have recently published the new testing methods for moisture in concrete, and those methods make ALL OTHER PUBLISHED METHODS FOR MOISTURE TESTING CONCRETE, THAT HAVE BEEN AROUND FOR MANY YEARS, OBSOLETE.  Don't let anyone tell you there are other certified testing methods.  There are not.  The new test method is, ASTM-F2170.  You can obtain that test, for a fee, by visiting <astm.org>.  That test method is for an entire concrete subfloor.  The test you may want to run would be for the small area exposed after you have taken up the 8 tiles and properly scraped away the old adhesive residue and the residue from the patching used for the cracked slab concrete.  However, remember that if you find there is a moisture problem, its source may be many feet away from the visible cracks, indicating all of the tiles must be removed.  I believe that test is done by drilling down into the slab about 40% of the thickness of the slab, with a 3/4 inch drill.  Then the sides of drill hole are to be covered with a plastic type moisture barrier.  The bottom of the drill hole should leave exposed concrete.  Then a RH capsule is inserted into the drill hole and left, UNDISTURBED, for 72 hours.  Once that time has passed, a meter is used at the top of the capsule which will indicate if there is any moisture problem in the concrete.  After the reading, the capsule will always remain in the concrete, and it is covered with a patching type leveler so the surface of the concrete is flat and smooth, and ready for the installation of a floor covering.  I believe Wagner Instruments, in Portland, Oregon, is one of the manufacturers of the capsules and moisture meter reader.  You can 'google' Wagner Instruments to view and purchase the needed products.  There is contact information, on that website, which, I think, is an 800 number.  Call it, speak with their technical services department, go over your entire problem with them, and they should be able to give you additional information.

Another option for you would be to contract with a certified, independent floor covering inspection service to view your installation, during the removal of the cracked tiles and then the exposed slab concrete.  Such an inspection may run in the upper $200 range.  I know MBD Floor Covering Inspection Service <mbdinspectfloors.com>, could do such an inspection.  I believe they have over 800 inspectors scattered throughout their service area, which is every city and town in all 50 States, in all The Provinces of Canada, parts of Mexico, the Caribbean Islands, The Provinces of Mainland China, and the Hong Kong area.  All they do is inspect and supply certified reports indicating their findings.

If you don't have a moisture problem, or installation and/or repair issues, there may be construction related failures causing the slab concrete and the tiles to crack.

All of that needs to be investigated, since if you 'try' things, such as patching, etc., you may find that you are just throwing money away.

If you have any other questions, please feel free to get back to me.

Cordially,

John Michaels